项目针对当前多用单一换水率来反映整条河流水体交换能力的局限与不足，围绕如何明晰多闸坝河网水体交换能力的时空分异特征及其多源驱动机制、并揭示其定量水质效应这一核心科学问题；以水龄作为表征河流水体交换能力时空分异性的指标，以发展闸坝调控大型河网一、二维嵌套的水动力-水龄-水质数值模型为基础，通过模拟水龄水质时空变化及闸坝调控的影响，从更高的时空分辨率量化多闸坝河网水体交换能力的变化特征；针对河网水龄的多源特性，通过水龄的数值源解析，以河网水龄组分谱的变化作为表征，来量化干支流不同水源丰枯变化及闸坝调控对水体交换能力的影响，揭示其变化的多源驱动机制；在此基础上，进一步挖掘河流水质的时空变化与水龄及其组分谱之间的定量响应关系，揭示多闸坝河网水体交换能力对污染物输移变化的影响。成果可从更高的时空分辨率量化河流水体交换能力的变化，有望突破单一换水率反映整条河流水体交换能力的局限；同时可从新的视角直观理解变化环境下多闸坝河网水文水动力过程改变的水环境效应，能为科学制定闸坝生态水量调度方案提供依据。

In order to break the limitation caused by a single exchange rate which is usually adopted to reflect the water exchange capacity of whole river, the following questions will be answered in this project: spatio-temporal variation characteristics of water exchange capacity in impounded river networks, its multi-source driving mechanism, and its quantitative water environmental effect. The water age is introduced to characterize spatio-temporal variation of water exchange capacity in river, and 4 tasks will be carried out: firstly, 1D&2D water age and water quality numerical model for large impounded river networks will be developed. Secondly, based upon long series of hydrological and water quality data, the spatio-temporal variation of water age and water quality will be simulated and the influence of dams will be analyzed to quantify the variation of water age in impounded river networks with higher spatial and temporal resolution. Thirdly, through numerical source analysis, the impact of different water sources and dams regulation on water exchange capacity will be quantified to reveal its multi-source driving mechanism. Lastly, through data mining, the quantitative response relationship between spatio-temporal variation of water quality and water age and its components will be inferred to reveal the impact of water exchange capacity on convection and change of water pollutants. Based upon the research results, water exchange capacity of river-networks will be quantified with higher spatial and temporal resolution to break the limitation caused by a single exchange rate; moreover, the water environmental effects of hydrology and hydrodynamics variation in impounded rivers will be interpreted more intuitively from a new vision, which could guide sluices ecological regulation schemes to realize their low environmental impact development.